Interstate highways are usually the last highways to close in bad weather, and one of the first to get serviced by snow-removers, de-icers, etc. That is because our supply chain relies on the ability of tractor-trailers to get stuff through. So if you see a gate that says "interstate closed", or have warnings ahead of time, go find a place to stay and wait it out.
My daughter and grandchildren came across a closed-I-70 this past spring. The interstate was closed westbound at Hays, KS. They were diverting traffic to a US highway, but she had made the error of not taking a map or atlas with her. They waited it out in Hays before deciding to turn around and head back home (central MO). So it does happen.
Donna